The United States Financial Crimes Enforcement Network, or FinCEN, recently proposed a series of new regulations applying to financial institutions dealing with digital currencies, such as Bitcoin (BTC). To summarize the proposed regulations, exchanges would essentially be required to file a report with FinCEN when a customer makes a purchase in excess of $10,000, and gather Know Your Customer information any time a transaction of $3,000 or greater is conducted using a non-custodial wallet.
This means that if a customer buys $3,000 worth of Bitcoin and withdraws it to a wallet they control, they would have to not only prove ownership of that wallet but also provide their name and physical address, along with additional identifying information.